The present invention relates to an electric actuator including a reduction gear and a control circuit board.
In the prior art, an electric actuator for a power window device includes a motor and a housing. The motor has a rotary shaft. The housing houses a reduction gear, which reduces the rotation speed of the rotary shaft. Japanese Laid-Open Patent Publication No. 2000-220344 describes an electric actuator having an actuator terminal, which may be connected to an external terminal such as a power supply. The actuator terminal is insert-molded with the housing so that the end of the terminal is exposed from the housing. In such an electric actuator, the insert-molded actuator terminal is exposed only at its end. Thus, there is no gap formed between the inside and outside of the housing. This prevents liquids, such as moisture, from entering the housing.
U.S. Pat. No. 5,245,258 describes another type of electric actuator including a housing that houses a control circuit board. The circuit board is arranged in a circuit board compartment. In addition to electric circuit components, an actuator terminal is arranged on the control circuit board. In such an electric actuator, insert molding is not performed. This facilitates the manufacturing of the housing.
In the electric actuator of U.S. Pat. No. 5,245,258, the housing must have an opening to expose the actuator terminal, which is arranged on the control circuit board, from the housing. However, if a gap is formed between the actuator terminal and the wall defining the opening, liquid may enter the housing and reach the circuit board compartment. This may damage the electric circuit components and motor.